With customers' higher demand for quality of electronic products, thickness of a flexible panel is developed to be thinner and thinner. With the development of smart phones and tablet computers, display screens are required to be lighter and thinner. Due to the limitations of the manufacturing, it is difficult to make the thickness of a glass substrate to be further thinner. Thus, it is focused on thinning down the thickness of the liquid crystal panel or the flexible panel after the alignment fitting or packaging of the panel to obtain a further thinner and lighter panel. In contrast to the liquid crystal panel, it is more difficult to thinning down the flexible panel, because during the process of thinning down the flexible panel, it is common to protect a reserved detection electrode on the flexible device by: covering a reserved detection hole of the reserved electrode on the panel with protection glue before etching, and removing such protection glue after the etching. However, such removing may reduce the precision of the grinding, and thus cause the device to be damaged.
Conventionally, it is difficult to totally remove the protection glue after the etching during the process of thinning down the flexible panel, which leads to that even tiny particulates of residual protection glue may severely reduce the measurement precision and cause the misjudgment of the quality of the flexible device, because the current detection of the flexible device is in a magnitude of nanoampere, and the demand of the precision of measurement is high. Furthermore, such misjudgment may affect the determination of the parameters for the preceding manufacturing process and the stability of the whole manufacturing process.
In the prior art, there are generally two types of grinding:
1. contact grinding: an end of a contact point contacts the flexible substrate, and the other end of the contract point contacts the reference point, so as to obtain the thickness of the whole flexible substrate;
2. non-contact grinding: the thickness of the whole flexible substrate is measured by a non-contacted optical sensor. Wherein, a key point lies in measuring the thickness between the etching side and a front side of the metal layer of the flexible substrate.
The distance from a bottom of the reserved conductive electrode to the etching side of the flexible substrate may be calculated based on the thickness measurement in the above two methods. However, in the non-contact grinding of the prior art, the substrate is measured directly by the light which is made only once, and then a grinding device is controlled to grind the panel to a desired thickness based on the measurement result, which may lead to the thickness of the panel to be in a significant deviation.